N-alkanol succinamic acid deicer



United States Patent 2,982,630 N-ALKANOL succrmuvnc ACID mucun Harry J. Andreas, Jr., Pitman, NJ., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Dec. 24, 1958, Ser. No. 782,659

' 3 Claims. (CI. 44-71) This invention relates to gasoline compositions adapted to improve the operation of internal combustion engines. It is more particularly concerned with motor fuels that provide improved engine operation under cool, humid weather conditions.

As is well known to those skilled in the art, frequent stalling of automobile engines, especially during the warmup period, has been a common occurrence. This difliculty is most pronounced in postwar cars having automatic transmissions and a consequent limit on the maximum permissible idle speed, although it also occurs in cars without automatic transmissions. Stalling of this type, of course, is a definite safety hazard, as well as a decided inconvenience in frequent restarting of the engine.

It is now recognized that stalling during the warmup period is attributable to the formation of ice on the throttle plate and the carburetor barrel near it. The water which forms the ice does not come from the gasoline, i.e., as entrained water, but from the air that enters the carburetor. As has been mentioned hereinbefore, stalling generally occurs incool, humid weather, when the temperatures are above about 30 F. and below about 60 F. and the relative humidity is about 65 percent and higher, up to 100 percent. The most critical conditions are temperatures of 3540 F. and 100 percent relative humidity.

As the gasoline evaporates in the carburetor, it reduces the temperature of the surrounding metal by as much as 40 F. Moisture in the incoming air comes in contact with these parts and begins to build up ice on the throttle plate and in the carburetor barrel. The more moist this air is, the greater the buildup of ice. Then, when the engine is idled, the throttle plate closes and the ice chokes off the normal small flow of air through the small clearance between the throttle plate and the carburetor wall. This causes the engine to stall. The engine can usually be restarted when the heat from the exhaust manifold melts the ice sufficiently. However, stalling will continue until the engine is completely warmed up.

Icing may also occur in the carburetors of some vehicles when cruising at speeds of 30-60 mph. Such icing is a particular problem in the case of certain trucks and cars equipped with carburetors having Venturi-type fuel-air mixing tubes (emulsion tubes). Such carburetors are found in trucks and in many European cars. The ice builds up in the tube and restricts the flow of air, thereby enriching the fuel mixture and reducing elficiency. Eventually the engine may stall.

Gasoline is a mixture of hydrocarbons having an initial boiling point falling between about 75 F. and about 135 F. and an end-boiling point falling between about 250 F. and about 450 F. The boiling range of the gasoline, of course, reflects on its volatility. Thus, a higher boiling gasoline will be less volatile and give less stalling difliculty. It has been proposed in the art that l; a gasoline having an A.S.T.M. mid-boiling 50%) point 2 of 310' F. or higher will not be subject to stalling. Although this may be the case for a given series of gasolines, however, it is not the sole and controlling factor.

Gasolines of higher mid-boiling point but a low initial boiling point (e.g., full boiling range gasolines) can induce stalling when the aforementioned stall-inducing atmospheric conditions are prevalent. Thus, any gasoline will give difliculty in damp, cool weather. In modern engine operation, however, control of stalling by means of volatility is not feasible, because other performance characteristics are affected.

It has now been found that stalling during engine warmup can be overcome simply and economically. It has been discovered that small amounts of certain N-alkanol succinamic acids, when added to motor gasoline, will overcome stalling difiiculties attributable to carburetor icing.

Accordingly, it is an object of this invention to provide an improved motor fuel. Another object is to provide a motor fuel adapted to prevent stalling during engine warmup in cool, humid weather. A specific object is to provide an anti-stall gasoline containing certain N-alkanol succinamic acids. Other objects and advantages of this invention will become apparent to those skilled in the art, from the following detailed description.

In general, this invention provides a motor gasoline containing a small amount, sufficient to inhibit stalling, of an N-ethanol alkenylsuccinamic acid.

The novel addition agents of this invention are the N-ethanol alkenyl succinamic acids, having between 8 and 16 carbon atoms in the alkenyl radical and, prefer temperature, but temperatures of about C. or low-' er are preferred. The time of reaction is dependent on the size of the charge and the reaction temperature selected. Ordinarily addition of the acid anhydride is substantially complete within a few minutes. In order to ensure complete reaction, however, it is preferred to continue heating for several hours, even as much as 10 hours. In general, the reaction time varies between several minutes and about ten hours. If desired, nonpolar solvents, such as benzene, toluene, xylene, and kerosines, can be used to improve fluidity.

Thealkenyl succinic acid anhydride reactant can have 8 to 16 carbon atoms in the alkenyl radical (prefer-' ably 10 to 14 carbon atoms). Non-limiting examples of the anhydride reactant are octenyl succinic acid anhydride, diisobutenyl succinic acid anhydride, Z-methyl heptenyl succinic acid anhydride, 2-ethyl hexenyl succinic acid anhydride, nonenyl succinic acid anhydride, undecenyl succinic acid anhydride, dodecenyl succinic acid anhydride, triisobutenyl succinic acid anhydride, A

tetrapropenyl succinic acid anhydride, tetradecenyl succinic acid anhydride, and hexadecenyl succinic acid anhydride.

Although the anhydride is preferred, the compounds of this invention can be prepared from the corresponding alkenyl succinic acid. In this case, the condensation with ethanolamine is accompanied by formation of one mole of water per mole of amine. The reaction, in this case, is carried out at temperatures of between about C.

and about 160 C., although the reaction can be efiected at temperatures above and below this range. The reaction will proceed until one mole of water is evolved per mole of alkenyl succinic acid reactant, usually six to ten hours. In order to facilitate the removal of water, to effect a more complete reaction in accordance with the principle of Le Chatelier, a hydrocarbon solvent which forms an azeotropic mixture with water can be added to the reaction mixture. Heating is continued until removal of water by azeotropic distillation has substantially ceased. Examples of well-known solvents that form azeotropes are benzene, toluene, and xylene.

The compounds of this invention can exist in either or both of the following structural forms:

R-CH--OH O Hri-NCHrCHzOH wherein R is an alkenyl radical of 8 to 16 carbon atoms, preferably 10 to 14 carbon atoms.

The amount of N-alkanol succinamic acid that is added to the motor gasoline will vary between about 0.005 percent and about 0.5 percent, by weight, of the gasoline. In preferred practice, amounts varying between about 0.01 percent and about 0.05 percent, by weight, are used.

The antistall additives of the invention may be used in the gasoline along with other antistall addition agents or other additives designed to impart other improved properties thereto. Thus, anti-knock agents, pre-ignition inhibitors, anti-rust agents, metal-deactivators, dyes, antioxidants, detergents, etc., may be present in the gasoline. Also, the gasoline may contain a small amount, from about 0.01 percent to about 1 percent, by weight, of a solvent oil or upperlube. Suitable oils, for example, include Coastal and Mid-Continent distillate oils having viscosities within the range of from about 50 to about 500 S.U.S. at 100 F. Synthetic oils, such as diester oils, polyalkylene glycols, silicones, phosphate esters, polypropylenes, polybutylenes and the like, may also be used.

The following examples are for the purpose of illustrating this invention and demonstrating the effectiveness thereof. This invention is not to be limited to the specific composition set forth in the examples or to the operations and manipulations involved. Other materials and formulations as described hereinbefore can be used, as those skilled in the art will readily understand.

The ability of an additive to inhibit icing is demonstrated in the following test:

HILLMAN-MINX ENGINE TEST A downdraft Solex FAI-30 carburetor was mounted on a standard 1953 Hillman-Minx engine. The engine was connected to a 7.5 horsepower induction motor and operated under load at 2800 r.p.m. This was equivalent to driving at about 40 miles per hour.

The Solex carburetor was especially prone to icing on its spraying well which is located in the center of the carburetor throat. The spraying well is a cylindrical metal tube with apertures through which a fuel-air mixture is sprayed into the carburetor throat. Evaporation of the fuel refrigerates the spraying well.

In conducting a test the engine was first run until the spraying well reached an equilibrium temperature of about 20-25 F. The fuel flow was then stopped and the engine was driven by the induction motor until the spraying well reached 45 F, (warm ambient air was admitted to the carburetor during this period). Fuel flow was now restored to the engine and the run was started. As the engine operated under load, ice deposited on the spraying well. The pressure drop across the ice formation was recorded at one-minute intervals for 20 minutes. Several tests were made on each fuel blend and the results were averaged.

A fuel rating was obtained by using these pressure readings to calculate the percentage of the carburetor throat area that would be blocked with ice after 20 minutes. The percent of annular area in the carburetor that is blocked by ice determines the amount of pressure drop across the annular opening in any given installation.

Thus, for each carburetor, the amount of throat area.

tionship between pressure drop and area blocked was determined to calibrate the carburetor, as follows:

A series of flanged cylinders were prepared, which fitted over the emulsion tube and blocked a portion of the annular opening. Each tube had a different, but known size flange. Thus, it was known what fraction of the annular area was blocked by each flange. The engine was operated with a flanged cylinder in the carburetor and the amount of pressure drop was noted and recorded. This operation was repeated with each flange.

From the data, thus obtained, the relationship between pressure drop and amount of throat area blocked was plotted. Then, when runs were made using blank fuel or inhibited (test) fuel, but with no flanged inserts in the carburetor, the throat area blocked by ice was determined from the amount of pressure drop. The average area blocked during the 20-minute run is obtained from the summation of the one-minute observations.

It will be appreciated, of course, that calibration curves will vary with each carburetor, but any carburetor can be readily calibrated as aforcdescribed. As is the case in many test procedures, results can vary from time to time, because' of slight variations in test conditions, vapor pressure of fuel, and even techniques of individual operators. Thus, each day a test-run is made, a blank fuel should be run. This provides a reference point, so that even if values determined may not be finite, comparison of a test fuel result with the result on the blank fuel gives a positive order of magnitude, i.e., one can say for example that an additive cut the amount of ice formation by some certain percentage.

The base gasoline was a blend, by volume, of 66 percent catalytically cracked gasoline, 2 percent natural gasoline, 12 percent benzene, 8 percent toluene, and 12 percent butane. It had an A.S.T.M. boiling range of F. to 394 F., with a mid-boiling point of 200 F.

Example The additive of the example was also blended in test gasoline and tested on the Hillman-Minx engine test. Pertinent data and results are set forth in Table I.

TABLE I Percent Annu- Additive Concn, Wt. Percent res Blocked With Ice 0.00 (blankl 45 0.01---- 27 0.05 12 0.00 (blank) 32 0.01 26 0 2 19 It will be apparent from the data in Table I that the substituted amic acids of this invention are effective antistall agents. Not all are equivalent in performance, but all will be elfective.

Although the present invention has been described with preferred embodiments, it is to be understood that, modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A motor gasoline containing a small amount, sumcient to inhibit icing, of an N-ethanol alkenyl succinamic acid, having between 8 and 16 carbon atoms per alkenyl radical.

2. A motor gasoline containing between about 0.005 percent and about 0.5 percent, by weight, of an N-ethanol alkenyl succinamic acid, having between 8 and 16 carbon atoms per alkenyl radical.

3. A motor gasoline containing between about 0.01 percent and about 0.05 percent, by weight, of an N-hydroxyethyl-tetrapropenyl succinamic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,604,451 Rocchini July 22, 1952 2,706,677 Duncan et al. Apr. 19, 1955 2,843,464 Gaston et al July 15, 1958 2,862,800 Cantrell et al. Dec. 2, 1958 2,886,423 Vitalis et a1 May 12, 1959 2,906,613 Mills Sept. 29, 1959 OTHER REFERENCES Petroleum Refining With Chemicals, Kalichkevsky and Kobe, Elsevier Pub Co., 1956, page 480. 

1. A MOTOR GASOLINE CONTAINING A SMALL AMOUNT, SUFFICIENT TO INHIBIT ICING, OF AN N-ETHANOL ALKENYL SUCCINAMIC ACID, HAVING BETWEEN 8 AND 16 CARBON ATOMS PER ALKENYL RADICAL. 